This invention is directed to the field of trigger dispensers, also known as trigger sprayers. The invention is particularly directed to a trigger sprayer having unique features enabling it to be used in both the upright and inverted positions.
Generally, a trigger sprayer is a relatively low cost pump device having a trigger. It may be grasped in the hand to pump liquid from a container and through a nozzle at the front of the sprayer in response to actuation of the trigger. The sprayer is connected to the container by a closure, and a dip tube or other passage provides fluid communication between the container and a pump element within the sprayer.
The pump element has an interior volume which decreases and increases in response to pulling and releasing the trigger, respectively. Check valves are positioned at the entrance and exit of the pump element to assure that fluid only flows in the proper direction through the sprayer. For instance, when the trigger is pulled, the volume of the pump element decreases and the liquid within the element is expelled past the exit check valve, through a barrel and out the nozzle orifice. At the same time, the entrance check valve is closed thereby inhibiting flow from the pump element to the container. Likewise, when the trigger is released, the volume of the pump element increases and liquid is drawn from the container, through the dip tube, past the entrance check valve and into the pump element. During this stroke the exit check valve is closed to inhibit flow from the barrel to the pump element.
There are numerous features which have become well-known in the trigger sprayer industry in addition to the basic configuration outlined above. For instance, some non-invertible sprayers include sealing means to prevent liquid from leaking from the nozzle orifices during shipment or non-use. Another feature of many non-invertible trigger sprayers is a vent system which prevents a vacuum from forming within the container as liquid is withdrawn. However, most typical trigger sprayers are not operable in the inverted position. If inverted operation is attempted, liquid is only dispensed until the dip tube is empty because the end of the dip tube is above the surface of the liquid in the inverted position. In addition, depending on the vent system used, liquid will drain through the vent with the sprayer inverted.
Several prior art trigger sprayers have been developed which permit a trigger sprayer dispenser to be used in inverted operation. For example, Yoshino German Patent 26 32 662 discloses a trigger dispenser having a housing extension which protrudes into the container. Two dip tubes extend from the housing extension; one tube extends to the bottom of the container, and the other extends to the top of the container. Ball valves are located at the junction of the extension and dip tubes. The ball valves shut off flow from whichever dip tube is oriented upward relative to the junction. However, the Yoshino patent does not provide for extended operation in either the upright or inverted position since a vent system is not included. Since the Yoshino sprayer does not have a vent system, a vacuum will develop in the container which will prevent liquid from being dispensed. Thus, air must periodically be introduced into the container thereby causing the user some inconvenience. In addition, the Yoshino housing extension and dip tubes are more bulky than a typical trigger dispenser. The size of the housing extension must be taken into account when designing a sprayer since the extension will not fit into a small-mouth container. Likewise, the assembly and disassembly of the trigger sprayer from the container are somewhat obstructed by the bulk of the extension and dip tubes.
Mann U.S. Pat. No. 5,119,974 discloses another invertible trigger sprayer apparatus. The Mann apparatus is a fairly typical trigger sprayer except that a tee junction is introduced partially down the dip tube, and a second dip tube is mounted on the tee so that the dip tube extends upward from the tee to the top of the container. Ball valves are positioned near the open end of each of the dip tubes to block flow in whichever dip tube is oriented upward. Although having a somewhat different configuration, the Mann design has the same shortcomings as the Yoshino design.
Rhea U.S. Pat. No. 5,195,664 discloses a trigger sprayer dispenser with a flexible dip tube extension which is weighted so that the end of the dip tube extends downward into the liquid no matter what the orientation of the container. However, like Yoshino and Mann, Rhea does not address the problems associated with the vent system, and requires a weighted head to be located within the container.
The patent of Blomquist U.S. Pat. No. 5,192,007 discloses another trigger sprayer which also may be used in the inverted position. Blomquist uses a traditional dip tube mounted to an adaptor plate connected to a fairly standard trigger sprayer. The adaptor plate incorporates two check valves. During inverted operation, one of the check valves closes to prevent liquid in the container from flowing out the vent passage. The other check valve opens when the pump element pressure decreases and liquid is drawn from the container, through the passage and into the pump element. However, liquid is also drawn from the dip tube during inverted operation thereby lowering the level of liquid in the dip tube. Thus, when the container is returned to the upright position, air is entrapped in the dip tube. Several trigger strokes are required to expel the air, during which liquid is either not dispensed or dispensed in a less than optimal pattern.
The present invention overcomes the disadvantages of the prior art trigger sprayers and provides a unique trigger sprayer which is operable in both the upright and inverted positions to produce a high quality spray without entrapping air and without leakage of liquid from the vent passage.